Electrochemical sensors are useful in chemistry and medicine to determine the presence or concentration of a biological analyte. Such sensors are useful, for example, to monitor glucose in diabetic patients and lactate during critical care events. A variety of intravascular, transcutaneous and implantable sensors have been developed for continuously detecting and quantifying blood analytes, such as blood glucose levels.
However, one of the major performance issues for continuous glucose sensors is drift in the sensitivity of the sensor in-vivo. In sensors comprising polymer membranes with hydrophobic and hydrophilic components, drift can be caused by rearrangement of the hydrophobic and hydrophilic polymer components to either bring more hydrophilic components to the surface or otherwise rearrange to allow for increased access to hydrophilic components during hydration of the membrane system. Thus, in-vivo sensors with improved surface wetting are desired.
Additionally, in-vivo sensors may be coated for targeted drug/biologic delivery. The drug or biologic for delivery is typically coated on the surface of the sensor, and ideally releases in-vivo in a controlled and predictable way. Thus, in-vivo sensors with surface treatments which allow for controlled and predictable release of a drug or biologic for delivery to a subject's blood or tissue upon implantation are desired.
Finally, in-vivo sensors are susceptible to fouling from nonspecific protein adsorption and cell adhesion. Additionally, in-vivo sensors may trigger inflammatory responses, such as leukocyte activation, tissue fibrosis, etc., which may adversely impact sensor performance. Thus, in-vivo sensors with surface treatments which resist nonspecific protein adsorption and cell adhesion and/or reduce inflammatory response of the host are desired.